Direct Observation of the Quantum Phase Transition of SrCu$_{2}$(BO$_{3}$)$_{2}$ by High-Pressure and Terahertz Electron Spin Resonance

Takahiro Sakurai; Yuki Hirao; Keigo Hijii; Susumu Okubo; Hitoshi Ohta; Yoshiya Uwatoko; Kazutaka Kudo; Yoji Koike

doi:10.7566/JPSJ.87.033701

paper

Direct Observation of the Quantum Phase Transition of SrCu $_{2}$ (BO $_{3}$ ) $_{2}$ by High-Pressure and Terahertz Electron Spin Resonance

arXiv:1801.08242 · doi:10.7566/JPSJ.87.033701

Abstract

High-pressure and high-field electron spin resonance (ESR) measurements have been performed on a single crystal of the orthogonal-dimer spin system SrCu $_{2}$ (BO $_{3}$ ) $_{2}$ . With frequencies below 1 THz, ESR signals associated with transitions from the singlet ground state to the one-triplet excited states and the two-triplet bound state were observed at pressures up to 2.1 GPa. We obtained directly the pressure dependence of the gap energies, finding a clear first-order phase transition at $P_{c} = 1.85 \pm 0.05$ GPa. By comparing this pressure dependence with the calculated excitation energies obtained from an exact diagonalization, we determined the precise pressure dependence for inter- ( $J^{'}$ ) and intra-dimer ( $J$ ) exchange interactions considering the Dzyaloshinski-Moriya interaction. Thus this system undergoes a first-order quantum phase transition from the dimer singlet phase to a plaquette singlet phase above the ratio $(J^{'} / J)_{c} = 0.660 \pm 0.003$ .

Direct Observation of the Quantum Phase Transition of SrCu $_{2}$ (BO $_{3}$ ) $_{2}$ by High-Pressure and Terahertz Electron Spin Resonance

Abstract

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Direct Observation of the Quantum Phase Transition of SrCu2​(BO3​)2​ by High-Pressure and Terahertz Electron Spin Resonance

Abstract

References in corpus (18)

Cited by in corpus (30)

Direct Observation of the Quantum Phase Transition of SrCu $_{2}$ (BO $_{3}$ ) $_{2}$ by High-Pressure and Terahertz Electron Spin Resonance